Natural Insect, Pest & Disease Control

Organic gardeners always prefer to use methods that have the least negative effect on the environment. By growing strong healthy plants we eliminate the threat of having large scale pest invasions.

But when some pest populations do build up in our garden we should be asking “how can I encourage more predators?”, rather than “what should I do about all these pests?”

For every pest you have in excess there is at least one, and probably many predators that would happily relieve you of the excess. Sometimes it takes predator populations a little longer to build than it does the pest it feasts on, so give it a little time before pulling out the big guns – insecticides.

Remember that ‘organic’ does not mean less poisonous and that most sprays are indiscriminate and really should only be used as a last resort. Bearing that in mind, here are some organic ways to deal with a few persistent bug problems.

 

Bug Juice

A very effective insecticide. Sounds a bit disgusting, but worth trying if you can stomach it!

Collect an assortment of pests – grasshoppers are excellent – from wherever you are having pest problems in your garden.

Liquefy them in a blender with the addition of one part water to about two parts in volume of bugs. Strain and dilute to about 5ml of bug juice per 1 litre of water. Spray on affected plants.

 

Snails and Slugs

Fortunately there are a few easy ways to deal with these ravenous creatures as they can devour your tender seedlings overnight.

Ducks are great snail and slug hunters and will delight wandering around the garden in search and destroy mode. The only minor damage you can expect is from their heavy feed, but they’ll generally not eat your greens like chooks would.

Of course you can collect the snails and slugs and throw them to your chooks if you keep them – they’ll be delighted! The best time for collection is dawn and dusk when it is moist. You can also make this job easier by having cardboard or similar on the ground where they will gather.

If you don’t have chooks or ducks another method is similar to the bug juice above. You need to gather some snails and/or slugs into a container with some added sugar and water. Allow it to ferment for a few days then place in the blender. You can dilute it further with water if you don’t have much ‘juice’ and sprinkle it around problem areas.

Another method is to make a coffee spray. This works by spraying it thoroughly on and around the seedlings you want to protect. When the snails or slugs cross areas that have been sprayed they absorb the caffeine and die.

Dilute one part strong espresso coffee to 10 parts hot water. When it’s cool, pour into a spray bottle and spray on plants that you want to protect and the immediate area around them.

Then there’s the time honoured traditional snail catcher – yes, the old beer in the jar trap. Partly fill a jar with beer (stale of course, you don’t want to waste the good stuff) and lay it on its side where they are most active. They are attracted to the beer, get drunk and die. What a way to go!

An alternative to this is vegemite dissolved in water. They are attracted to the yeast.

Mealy bugs look like white, fluffy slaters. They are sap-sucking insects that cause leaves to wilt and go yellow. You may find them feasting away on your fruiting plants and ornamentals such as palms, ferns, orchids and succulents.

They prefer the sheltered conditions of a glass house or indoors. Mealy bugs exude a sweet, sticky substance called honeydew which can lead to sooty mould fungus and ants (ants feed on the honeydew).

The best way to deal with them is to prune off the most damaged parts of the plant and then kill any remaining bugs by dabbing them with a cottonwool ball dipped in methylated spirits. This will dissolve their waxy protective coating, they will dehydrate and die.

Scale are also sucking insects that feed on plant sap. They form in thick clusters on the leaves and soft growth of many garden plants. They also produce honeydew as a waste by-product of their feeding. Heavy infestations can cause stunted growth and wilting.

If you only have a small infestation you can scrape them off your plant with your fingernail or a toothbrush. Larger numbers can be sprayed with a solution of homemade oil spray.

You can also use the oil spray to eliminate citrus leaf-miner and red spider mite. When you coat them thoroughly, the pests are suffocated by the oil.

 

Home-made oil spray.

1. Add 500ml of vegetable oil to 250ml of pure liquid soap to a bowl.

2. Mix together in a blender and then store in a jar.

3. Dilute 1 tablespoon in 1 litre of water. Spray, making sure you get under all the leaves.

Special Note: Have kitchen utensils and a blender that are dedicated specifically for the purpose of spray preparation.

Use all sprays with extreme caution and do not eat from any plant that has been sprayed for at least two weeks.

Controlling insects and pests naturally can sometimes be difficult. Here are some of the best ways to help reduce your losses without resorting to harmful chemicals.

  Choose disease resistant varieties

  Discard sickly looking seedlings

  Keep your plants growing vigorously

  Clean up crop waste as quickly as practical

  Keep out weeds which encourage insects and disease

  Hand-pick insects like caterpillars, hose off aphids

  Water at soil level, so plants are not wet at night

  Dispose of any diseased plants before they contaminate others

  Don’t throw diseased plants in your compost heap

  Rotate your garden beds / plots

  Encourage natural predators wherever possible

  Insect traps can work for snails and slugs

 

Deterring Pest Birds

Blackbirds are a real pest in my veggie garden here in the Barossa Valley, South Australia. They look for insects and grubs on the ground with their feet and beaks by pushing around mulch and leaf-litter.

This really annoys me when I’ve just laid out a fresh layer of mulch because they make such a mess and sometimes end up burying or damaging my plants.

So I tried a little experiment with several rubber snakes around my veggie plots to see if it makes a difference. Guess what? It actually works, provided I move the snakes to different positions each day.

Remove their nests if you find them under your eaves or verandas, to discourage them breeding around your property. They build medium to large fibre and mud nests.